Well, we'd better not compare Rome and the Seleucids.this is a comparison of Rome's longevity
When in OTL Antiochus the Great went against Rome it was like being hit with a truck
They were not in the same league. You know what I mean.
You cannot compare their power base.
Antiochus the Great lost two battles and the Seleucid empire declined.
How many battles did Rome loose to Hannibal? And what?
Roman statehood was the most extraordinary unique thing in the history of the humankind. Especially its longevity.